Reflective coding panel and reflective coding LCD

ABSTRACT

The present invention provides a reflective coding panel and a liquid crystal display. The liquid crystal display includes a panel, a reflective coding layer formed on the panel, and a polarizing plate positioned on the reflective coding layer, wherein the reflective coding layer includes a plurality of cholesteric liquid crystal flakes having a pitch length and an average reflective index, and the pitch length multiplied by the average reflective index is within a range of an infrared ray wavelength.

FIELD OF THE INVENTION

This invention relates to a panel and a liquid crystal display, and more particularly to a reflective coding panel and a reflective coding liquid crystal display.

BACKGROUND OF THE INVENTION

Currently, the touch input devices are widely used. According to the conventional touch input technologies, the touch input devices include sensors based on a resistance and sensors based on a capacitance, i.e. the touched position on the touch input device is identified by measuring the electrical potential changes via a circuit. Recently, the optical touch input technology is developed, i.e. the touched position is identified by identifying the optical images. For the optical touch input device, the information can be entered by writing on a specific coding arrangement via a light pen, wherein the specific coding arrangement is fabricated on the substrate of the optical touch input device. The coding arrangement is exposed to the light emitted from the light pen, and then the light is reflected to the image-detecting system. Then, the coding is obtained by identifying the detected images, so that the optical touch input is effected.

The cholesteric liquid crystal has a structure similar to the cholesterol molecule. The cholesteric liquid crystal is made up of spirally oriented stick-like “nematic liquid crystals”, wherein “chiral molecules” are added into the “nematic liquid crystals”, and molecules in the different layers of the cholesteric liquid crystal orient at a slight angle relative to each other, so that the cholesteric liquid crystal has a spiral structure.

Due to the optical activity and the spiral structure of the cholesteric liquid crystals, the light passing through the cholesteric liquid crystals is split into the right-circularly polarized wave and the left-circularly polarized wave. The 50% of the light with the optical activity identical to that of the cholestreic liquid crystals is reflected. Accordingly, the cholesteric liquid crystals are widely used duo to the high reflection thereof. For example, U.S. Pat. No. 6,753,044 B2 discloses a coloring media including cholesteric liquid crystal flakes has the improved reflection characteristics of the red, green and blue colors. And the U.S. Pat. No. 6,727,967 B2 discloses a half-transmission color liquid crystal display, wherein a phase difference plate and a liquid-crystal layer are provided between a polarizing plate and a cholesteric liquid crystal layer. In the U.S. Pat. No. 6,727,967 B2, when the liquid crystal display device functions as a reflective liquid crystal display, light entering through the polarizing plate is reflected by the cholesteric liquid crystal layer; however, when the liquid crystal display device functions as a transmission liquid crystal display, light from the backlight passes through the cholesteic liquid crystal layer, and thereby the brightness and the color density of the liquid crystal display device are improved.

Up to now, the brightness, contrast, the reaction time and the cost of the liquid crystal display stilled should be improved. The present invention provides a reflective coding panel and a reflective coding liquid crystal display, wherein the optical touch input technology and the cholesteric liquid crystals are integrated into a panel or a display, so that the reflective coding panel and the reflective coding liquid crystal display of the present invention are touch input devices with a great reflection.

SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide a reflective coding liquid crystal display, which is formed by integrating the optical touch input technology and has optical characteristics of the cholesteric liquid crystals. The reflective coding liquid crystal display includes a panel, a reflective coding layer formed on the panel, and a polarizing plate positioned on the reflective coding layer, wherein the reflective coding layer comprises a plurality of cholesteric liquid crystal flakes having a pitch length and an average reflective index, and the pitch length multiplied by the average reflective index is same as the wavelength of reflected light within a range of an infrared ray. In addition, the reflective coding layer also could be a material for absorbing the infrared ray but passing the visible light passing therethrough.

It is another aspect of the present invention to provide a reflective coding panel, which is formed by integrating the optical touch input technology and has optical characteristics of the cholesteric liquid crystals. The panel includes a substrate and a reflective coding layer formed on the substrate, wherein the reflective coding layer comprises a plurality of cholesteric liquid crystal flakes having a pitch length and an average reflective index, and the pitch length multiplied by the average reflective index is within a range of an infrared ray wavelength. In addition, the reflective coding layer also could be a material for absorbing the infrared ray but passing the visible light passing therethrough.

Preferably, the substrate is a transparent substrate.

Preferably, the substrate is a glass substrate, a color filter substrate or a polarizing plate.

The above aspects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a schematic view illustrating the reflective coding liquid crystal display according to the first embodiment of the present invention;

FIG. 1(b) is a schematic view illustrating the touch input liquid crystal display according to the first embodiment of the present invention;

FIG. 2(a) is a schematic view illustrating the reflective coding liquid crystal display according to the second embodiment of the present invention;

FIG. 2(b) is a schematic view illustrating the touch input liquid crystal display according to the second embodiment of the present invention;

FIG. 3(a) is a schematic view illustrating the reflective coding panel according to the third embodiment of the present invention; and

FIG. 3(b) is a schematic view illustrating the touch input panel according to the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention is described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for the purpose of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.

Please refer to FIG. 1(a), which is a schematic view illustrating the reflective coding liquid crystal display 1 according to the first embodiment of the present invention.

The reflective coding liquid crystal display 1 includes a first substrate 11, a second substrate 12, a liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12, a first polarizing plate 14 disposed under the first substrate 11, a reflective coding layer 15 disposed above the second substrate 12, and a second polarizing plate 16 disposed on the reflective coding layer 15.

The first substrate 11 and the second substrate 12 can be transparent substrates or the color filter substrates. The liquid crystal layer 13 consists of liquid crystal molecules. The reflective coding layer 15 includes a plurality of cholesteric liquid crystal molecules and a medium, and is fromed on the second substrate 2 by one of inkjet printing, screen printing or relief printing. The printed patterns on the reflective coding layer 15 are dependent on the coding arrangement, which is required. The medium can be an ink, a paint or a volatile solvent for the cholesteric liquid crystal flakes being evenly dispersed therein to be further encoded and printed. The cholesteric liquid crystal flakes have a pitch length and an average reflective index. In accordance with the present invention, the pitch length multiplied by the average reflective index is within a range of an infrared ray wavelength (700 nm-300 k nm). Preferably, the pitch length multiplied by the average reflective index is ranged from 700 nm to 1700 nm. More preferably, the pitch length multiplied by the average reflective index is ranged from 910 nm to 940 nm. It means that the infrared ray with the wavelength from 910 nm to 940 nm can be reflected by the reflective coding liquid crystal display 1. In addition, the reflective coding layer 15 also could be a material for absorbing the infrared ray but passing the visible light passing therethrough. For example, the material can be SDA7775, SDA7779, SDA4850 or SDA8737 (H. W. Sand Corp.).

Please refer to FIG. 1(b). According to the present invention, since the infrared ray with the wavelength from 910 nm to 940 nm can be reflected by the reflective coding liquid crystal display 1, a light pen 17 can be applied to the reflective coding liquid crystal display 1 for emitting the infrared ray and detecting the images, wherein the light emitted from the light pen to the reflective coding layer is reflected to the image detection system, and then according to the different brightness among the reflected infrared rays, the image is detected and identified, so that the position having such coding is obtained. It is advantageous to avoid the visible light absorbed by the coding patterns, influencing the brightness of the display. Certainly, the reflective coding liquid crystal display 1 with a light pen 7 function as an optical touch input device. Furthermore, the reflective coding liquid crystal display 1 has the cholesteric liquid crystal flakes 151 with the high reflection, so that the reflective coding liquid crystal display 1 has not only the great effects on providing the light source with great reflectivity and power-saving, but also high brightness.

Please refer to FIG. 2(a), which a schematic view illustrating the reflective coding liquid crystal display 2 according to the second preferred embodiment of the present invention.

The reflective coding liquid crystal display 2 includes a first substrate 21, a second substrate 22, a liquid crystal layer 23 disposed between the first substrate 21 and the second substrate 22, a first polarizing plate 24 disposed under the first substrate 21, a second polarizing plate 25 disposed above the second substrate 22, and a reflective coding layer 26 disposed on the second polarizing plate 25.

The first substrate 21 and the second substrate 22 can be transparent substrates or color filter substrates. The liquid crystal layer 23 consists of liquid crystal molecules. The reflective coding layer 26 includes a plurality of cholesteric liquid crystal molecules 261 evenly dispersed in a medium, and the reflective coding layer 26 is formed on the second polarizing plate 25 by inkjet printing, screen printing or relief printing. The printed patterns on the reflective coding layer 26 are dependent on the coding arrangement, which is required. The medium can be an ink, a paint or a volatile solvent for the cholesteric liquid crystal flakes being evenly dispersed therein to be further encoded and printed. According to the present invention, the cholesteric liquid crystal flake 261 has a pitch length and an average reflective index, and the pitch length multiplied by the average reflective index is within a range of an infrared ray wavelength (700 nm-300 k nm). The preferable infrared ray wavelength is ranged from 700 nm to 1700 nm. Most preferably, the infrared ray wavelength is ranged from 910 nm to 940 nm. Therefore, the infrared ray with the wavelength from 910 nm to 940 nm can be reflected by the reflective coding liquid crystal display 2. In addition, the reflective coding layer 26 also could be a material for absorbing the infrared ray but passing the visible light passing therethrough. For example, the material can be SDA7775, SDA7779, SDA4850 or SDA8737 (H. W. Sand Corp.).

Please refer to FIG. 2(b). According to the present invention, since the infrared ray with the wavelength from 910 nm to 940 nm can be reflected by the reflective coding liquid crystal display 2, a light pen 27 can be applied to the reflective coding liquid crystal display 2 for emitting the infrared ray and detecting the images, wherein the light emitted from the light pen to the reflective coding layer is reflected to the image detection system, and then according to the different brightness among the reflected infrared rays, the image is detected and identified, so that the position having such coding is obtained. It is advantageous to avoid the visible light absorbed by the coding patterns, influencing the brightness of the display. Certainly, the reflective coding liquid crystal display 2 with a light pen 27 functions as an optical touch input device. Furthermore, the reflective coding liquid crystal display 2 has the cholesteric liquid crystal flakes 261 with the high reflection, so that the reflective coding liquid crystal display 1 has not only the great effects on providing the light source with great reflectivity and power-saving, but also high brightness.

Please refer to FIG. 3(a), which a schematic view illustrating the reflective coding panel 3 according to the third preferred embodiment of the present invention. The reflective coding panel 3 includes a substrate 31 and a reflective coding layer 32 disposed on the substrate 31.

The substrate 31 can be a transparent substrate, a glass substrate, a color filter substrate or a polarizing plate. The reflective coding layer 32 consists of cholesteric liquid crystal flakes 321 evenly disposed in a medium, and is formed on the substrate 32 by inkjet printing, screen printing or relief printing. The printed patterns on the reflective coding layer 32 are dependent on the coding arrangement, which is required. The medium can be an ink, a paint, or a volatile solvent for the cholesteric liquid crystal flakes being evenly dispersed therein to be further encoded and printed. According to the present invention, the cholesteric liquid crystal flake 321 has a pitch length and an average reflective index, and the pitch length multiplied by the average reflective index is within a range of an infrared ray wavelength (700 nm-300 k nm). The preferable infrared ray wavelength is ranged from 700 nm to 1700 nm. Most preferably, the, infrared ray wavelength is ranged from 910 nm to 940 nm. Therefore, the infrared ray with the wavelength from 910 nm to 940 nm can be reflected by the reflective coding panel 3. In addition, the reflective coding layer 32 also could be a material for absorbing the infrared ray but passing the visible light passing therethrough. For example, the material can be SDA7775, SDA7779, SDA4850 or SDA8737 (H. W. Sand Corp.).

Please refer to FIG. 3(b). According to the present invention, since the infrared ray with the wavelength from 910 nm to 940 nm can be reflected by the reflective coding panel 3, a light pen 33 can be applied to the reflective coding panel 3 for emitting the infrared ray and detecting the images, wherein the light emitted from the light pen to the reflective coding layer is reflected to the image detection system, and then according to the different brightness among the reflected infrared rays, the image is detected and identified, so that the position having such coding is obtained. It is advantageous to avoid the visible light absorbed by the coding patterns, influencing the brightness of the display. Certainly, the reflective coding panel 3 with a light pen 33 functions as an optical touch input device. Furthermore, the reflective coding panel 3 has the cholesteric liquid crystal flakes 321 with the high reflection, so that the reflective coding panel 3 has not only the great effects on providing the light source with great reflectivity and power-saving, but also high brightness.

Accordingly, the optical touch input technology and the cholesteric liquid crystal molecules are integrated in the panel of the present invention, and thereby the touch input liquid crystal display and panel with great reflection are provided. Certainly, the present invention has the industrial applicability.

While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures. 

1. A liquid crystal display, comprising: a panel; a reflective coding layer formed on said panel; and a polarizing plate positioned on said reflective coding layer, wherein said reflective coding layer comprises a plurality of cholesteric liquid crystal flakes having a pitch length and an average reflective index, and said pitch length multiplied by said average reflective index is within a range of an infrared ray wavelength.
 2. The liquid crystal display according to claim 1, wherein said cholesteric liquid crystal flakes are evenly dispersed in said reflective coding layer via a medium.
 3. The liquid crystal display according to claim 2, wherein said medium comprises one of a volatile solvent, an ink, and a paint.
 4. The liquid crystal display according to claim 1, wherein said reflective coding layer is formed on said panel by one selected from a group consisting of an inkjet printing, a screen printing and a relief printing.
 5. The liquid crystal display according to claim 1, wherein said infrared ray wavelength is ranged from 700 nm to 1700 nm.
 6. The liquid crystal display according to claim 1, wherein said infrared ray wavelength is ranged from 910 nm to 940 nm.
 7. A panel, comprising: a substrate; and a reflective coding layer formed on said substrate, wherein said reflective coding layer comprises a plurality of cholesteric liquid crystal flakes having a pitch length and an average reflective index, and said pitch length multiplied by said average reflective index is within a range of an infrared ray wavelength.
 8. The panel according to claim 7, wherein said substrate is a transparent substrate.
 9. The panel according to claim 7, wherein said substrate is a polarizing plate.
 10. The panel according to claim, 7, wherein said cholesteric liquid crystal flakes are evenly dispersed in said reflective coding layer via a medium.
 11. The panel according to claim 10, wherein said medium comprises one of a volatile solvent, an ink, and a paint.
 12. The panel according to claim 7, wherein said reflective coding layer is formed on said panel by one selected from a group consisting of an inkjet printing, a screen printing and a relief printing.
 13. The panel according to claim 7, wherein said infrared ray wavelength is ranged from 700 nm to 1700 nm.
 14. The panel according to claim 7, wherein said infrared ray wavelength is ranged from 910 nm to 940 nm.
 15. A touch panel, comprising: a substrate; and a reflective coding layer patterned on said substrate, wherein said reflective coding, layer absorbs an infrared ray but passes invisible light for displaying a specific pattern.
 16. The panel according to claim 15, wherein said substrate is a transparent substrate.
 17. The panel according to claim 15, wherein said reflective coding layer is patterned on said panel by one selected from a group consisting of an inkjet printing, a screen printing and a relief printing.
 18. The panel according to claim 15, wherein said infrared ray wavelength is ranged from 700 nm to 1700 nm.
 19. The panel according to claim 15, wherein said infrared ray wavelength is ranged from 910 nm to 940 nm. 